The present invention relates to a method of carrying photosensitive materials in parallel rows in a photographic printer machine to prevent its transfer sections from being fouled during the development process.
Common photographic printers are designed in which a continuous strip of material is supplied from a roll, exposed to light on an exposure bed in the exposure station to print frames of images from a negative film, passed through tanks filled with developing liquids, and dried out before being unloaded.
The strip of photosensitive material exposed on the exposure bed is separated into pieces of a frame size for ease of the development process. A resultant series of frame pieces are transferred to the development station in a row while spaced one from another by some tens of millimeters so that they do not overlap each other in the development station.
In such a conventional photographic printer machine, the photosensitive materials are processed at a slower speed in the development station than in the exposure station. For increasing the performance speed of the conventional photographic printer machine, it is essential to improve the processing capability at the development station.
Although the feeding speed of the photosensitive material in a single row has been adjusted to a fastest possible rate, it has a substantial limitation. In a modification, the transfer section in the development station has an increased rack length to process a greater number of frames of photosensitive material in a given time. The longer the rack length, the faster the transfer speed across the development station is determined.
However, as the rack length of the transfer section is increased, the overall length of the development station increases. This requires larger tanks and thus larger amounts of developing liquids and more liquids needed for replenishment. If the processing ability is increased, for example, from 500 frames/time to 1000 frames/time while the width of the frame of the photosensitive material remains unchanged, the rack length has to be increased by about 2.1 times, the amounts of the developing liquids by 2 times, and the liquid replenishments also by 2 times.
To overcome the foregoing disadvantages of the conventional development station, we, the applicants, proposed in our previous application a modified development method and its apparatus in which the frame pieces of the photosensitive material transferred from the exposure station are alternately dislocated from a transfer path to the left and to the right to have a zigzag form before being fed to the development station.
A drawback of the method and the apparatus is that while the frame pieces of the photosensitive material are carried in two rows over transfer rollers in the development station, they leave dirt on intermediate regions of the rollers between two rows. If a wider size of the photosensitive material is introduced into the development station, it runs over the intermediate regions of the rollers and will thus be fouled with the dirt.
Such dirt or waste results from oxidation and deterioration of chemical ingredients of the developing liquids which may be caused with time and when the temperature is changed during a long run of the development process. The dirt on the transfer rollers may more or less tar the edges of the frame pieces which run in two rows. There are thus needed some extra maintenance tasks of cleaning the rollers and their support rack and replacing the developing liquids with fresh ones or replenishing periodically for retarding the deterioration of the developing liquids.